In a wireless local area network (hereinafter “wireless LAN”) based on the IEEE 802.11b standard, as depicted in FIG. 11, for example, a total of 14 channels with bandwidth of 22-24 megahertz (hereinafter denoted as MHz) with a center frequency of 2412-2384 MHz are assigned for exchange of information, for the purpose of wireless LAN communication. A wireless LAN is composed of an access point composed of a base station that is the center of the wireless LAN, and a terminal device which is a mobile unit, with wireless LAN communications being carried out between these wireless LAN devices. Each wireless LAN device on a single wireless LAN cannot simultaneously perform wireless LAN communication on different channels; rather, all wireless LAN communication is performed using a single selected channel. Radio wave status on this selected channel can be adversely affected due to various causes. Radio wave status can be adversely affected by communication conflicts arising when the same channel is used by a large number of wireless LAN devices, by radio wave interference occurring when other wireless LAN devices located nearby use an overlapping frequency band, or by radio wave interference with radio waves output by other devices that are not wireless LAN devices. If a channel with deteriorated radio wave status is used for wireless LAN communications, wireless LAN communication speeds may drop, or communication may become impossible.
As an access point that is able to deal with such deterioration of radio wave status, there is known in the art to date an access point that using communication means for carrying out wireless LAN communications detects radio wave status on multiple channels, and reselects a channel based on the detected radio wave status. This access point periodically interrupts wireless LAN communications to detect radio wave status on multiple channels using the communication means that was carrying out wireless LAN communications. On the basis of the detected radio wave status, it reselects a channel suitable for communications, switches the system to the reselected channel, and reopens wireless LAN communication. As a result, the prior art access point, when encountering deterioration of radio wave status on the channel on which wireless LAN communications are being performed, can switch to a channel with better radio wave status and reopen wireless LAN communication, thus avoiding a drop in communication speed or inability to communicate due to deteriorated radio wave status.
Japanese Published Unexamined Patent Application No. 2002-158667 teaches an access point that uses the communication means for carrying out wireless LAN communications to detect radio wave status of multiple channels, and reselects a channel based on detected radio wave status.
However, with the prior art access point, it was necessary to interrupt wireless LAN communications periodically in order to detect radio wave status. Since information cannot be exchanged during interruption of wireless LAN communications, a resultant problem was that, in instances of good communication for example, effective communication speed is actually lower.
With the foregoing in view, it is an object of the present invention to provide an access point that is able to avoid lowering effective communication speed due to detection of radio wave status for performing channel reselection.